Experimental results for uniformity and IEDF control with phase-locked RF source and bias on an inductively coupled plasma system

Summary form only given. A vexing challenge for inductively coupled plasma sources is the uniformity effect of gas flow, pressure regulation, and RF field emissions from the top coil antenna and its coupling with the electrode bias. These three entities can impair symmetrical flow and adversely impinge pattern etching across the wafer. We focus our effort on controlling the amplitude and phase relation of a dual coil driven antenna and thereby the EM field emission uniformity. Industry has long countered this challenge by affecting the electric field with a various approaches: (1) a permanent magnet assembly around the periphery of the substrate, (2) coil geometry arrangement, (3) RF source pulsing, (4) controlling the ratio of the coil currents, or (5) non-similar frequency assignments to the coils of the antenna structure. With EM field simulations, we previously showed by amplitude and relative phase manipulation of the RF excitation for the source coil arrangement, the controllability of the constructive-deconstructive interaction of the coil fields to positively affect plasma density and associated uniformity along the wafer area.¹ We demonstrate this uniformity by measuring the ion flux along the bias diameter. We further explore the quantitative benefits of tailoring ion energy distribution functions with the phase interaction between the RF powered bias and the source RF power delivery system. The RF bias, coupled to the substrate, produces ion energies utilized for pattern-etch processing associated with high-volume semiconductor manufacturing. Our fundamental technique is based on a frequency-and-phase locking controller with plurality instantiations in the source RF power delivery system and the bias RF power supply. With precise control of the electromagnetic field emissions, our systematic control of plasma parameters yields enhancements toward uniformity improvement commensurate with IEDF generation, all necessary improvements for next gene- ation plasma processing systems.